The long term objective of this work is to develop a new method of intra articular imaging to overcome current limitations in reheumatologic diagnostic imaging. Recent reports suggesting that the progression of articular cartilage damage in osteoar-thritis may be modified have heightened the need for better methods to image early changes in cartilage and monitor the progression of these changes. A variety of imaging modalities have been applied to the assessment of early osteoarthritic abnormalities with limited results. The hypothesis is that optical coherence tomography (OCT), a new method of fiber optic based micron scale imaging, can be developed as a method of high resolution, minimally invasive, intra articular imaging to address current limitations in joint diagnostics. OCT is analogous to ultrasound B mode imaging using infrared light rather than acoustical waves. OCT is attractive for intra articular diagnostic imaging because of its high resolution (4-20 um), broad dynamic range (110 dB), small compact design and ability to perform imaging through small optical fibers. The applicants proposed to test the hypothesis principally through background feasibility experiments designed to assess the ultimate utility of the approach. These background experiments focus on identifying advantages and limitations of OCT for intra articular imaging and maximizing performance. The specific aims are to: 1. To perform imaging on a wide range of articular cartilage to identify limitations and advantages associated with OCT imaging. 2. To use the quantitized nature of light-molecular interaction to spectroscopically explore the biochemical changes of osteoarthritic articular cartilage. 3. To demonstrate the ability of OCT to perform in vivo imaging in a rabbit knee joint.